Method for producing a shoe sole

ABSTRACT

A shoe includes a sole structure that defines a first supporting structure, a second supporting structure, and a third supporting structure, the first supporting structure being disposed within a forefoot region, the second supporting structure being disposed within a midfoot region, and the third supporting structure being disposed within a heel region. Each of the first supporting structure, the second supporting structure, and the third supporting structure define at least one curved surface, against which a plurality of plastic bodies are disposed. The plurality of plastic bodies comprise foamed plastic, define spheres or ellipsoids, are between 1 mm and 13 mm in the three spatial directions, and are arranged loosely within the sole structure without connection to one another. The plurality of plastic bodies are compressed against the first supporting structure, the second supporting structure, and the third supporting structure.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/095,239, filed on Oct. 19, 2018, which claims priority toInternational Application No. PCT/EP2016/002066, filed Dec. 8, 2016, theentire contents of which are incorporated by reference herein in theirentirety.

BACKGROUND OF THE INVENTION

The invention relates to a method for producing a shoe sole, especiallyof such for a sports shoe.

The production of shoe soles especially for sports shoes is asufficiently known technology. Thereby not only an economical processfor the production is aimed for but also to have the possibility to havea possibly good influence onto the spring and damping behavior of theshoe sole and thus of the shoe. Here, also the used material has asignificant influence.

SUMMARY OF THE INVENTION

In U.S. 2009/0013558 A1 a shoe is described at which the shoe soleconsists of different plastic materials which are connected withanother, wherein different polymer materials are used. In WO 2007/082838A1 is described that also expanded thermoplastic polyurethane (E-TPU)can be used beneficially for a shoe sole. In this documents alsodetailed information is contained for this plastic material; insofarexplicitly reference is made to this document.

Also in DE 10 2011 108 744 B4 a shoe is described at which E-TPU is usedas material for the sole. Here, it is furthermore described that singlefoamed plastic spheres, which have mostly a dimension of fewmillimeters, made of this material are formed to the sole in such amanner that a binder is added into a respective tool according to apossible embodiment so that the plastic spheres are connected withanother and form the body of the sole. According to another processwater steam under defined pressure is applied to a tool in which theplastic spheres are imported. Thereby, a partial melting of the plasticmaterial occurs so that the plastic spheres are connected with anotherby positive substance jointing and thus form the body of the sole.

The properties of the shoe which are so obtainable, especially withrespect to the spring and damping behavior, are not fully satisfactoryin any case. Furthermore, the production process of the mentioned soleis sometimes elaborate and thus costly.

Thus, it is the object of the invention to provide a method by which ashoe sole can be produced in a cost efficient manner and which springand damping behavior can be adjusted in a desired manner. Thus, the shoesole should be producible economically and with easy adjustable springand damping properties.

The solution of this object by the invention is characterized in thatthe method comprises the following steps:

a) Extruding a plastic hose and feeding the plastic hose into a blowmold or injection molding of a plastic blank and feeding the plasticblank into a blow mold;

b) Blow molding the plastic hose or the plastic blank into a sole hollowbody, wherein recesses are introduced on mutually opposing walls of thesole hollow body during the blow molding process, such that parts of thewalls are brought into contact with one another and form a supportingstructure between the mutually opposing walls;

c) Removing the blow-molded sole hollow body from the blow mold;

d) at least partially, preferably completely, filling the blow-moldedsole hollow body with plastic bodies, wherein the plastic bodies areadded through a first opening in the sole hollow body.

As plastic bodies especially spheres, ellipsoids or cylinders are used.The dimensions of the single plastic bodies in the three specialdirections are preferably between 1 mm and 13 mm, specificallypreferably between 3 mm and 6 mm. The plastic bodies consist therebyespecially of foamed plastic material.

As the material for the plastic bodies preferably used is expandedthermoplastic polyurethane (E-TPU), expanded thermoplastic elastomere(E-TPE) (especially expanded thermoplastic elastomere based on olefin(E-TPO)) and/or expanded polypropylene (EPP).

The sole hollow body consists however preferably of thermoplasticpolyurethane (TPU), of thermoplastic elastomere (TPE), of polyamide (PA)and/or of rubber material.

A preferred embodiment of the method proposes that after above step d) asealing, especially a welding, of the first opening occurs.

Furthermore it can be provided that during or after above step d) anevacuation of air from the sole hollow body occurs. This occurspreferably via a second opening which is disposed at a distance from thefirst opening.

Thereby, the plastic bodies are preferably arranged in the sole hollowbody without connection to another. Accordingly, the single spheres orellipsoids are not connected with another by any measures but arearranged loosely in the sole hollow body.

The plastic bodies are thereby preferably arranged in full package andpreferably under pressure in the sole hollow body.

The production of the supporting structure takes place preferably bycreating one of the recesses with the closed end region into one of thewalls by means of a first deformation tool and by creating the otherrecess with the open end region into the other wall by means of a seconddeformation tool, wherein the closed end region of one of the recessesis designed for entry into the open end of the other recess. By doing sovery beneficially a spring and damping element respectively in the kindof a piston-cylinder-system is realized. At intended use of the shoewhich is equipped with the described shoe sole thus relative movementsbetween the two recesses in vertical direction can occur (when the shoesole stands on the ground). By the choice of the geometry of the tworecesses and especially of the closed end region at the one hand and theopening in the other recess at the other hand the spring rate of thesole in vertical direction as well as its damping behavior can beinfluenced.

An embodiment of the method provides that prior to closing of the blowmold and carrying out of above step b) an insert is placed into the blowmold so that the insert connects with the sole hollow body during theblow molding process.

The insert can be pre-fabricated by an injection molding process. Theinsert has according to a preferred embodiment a U-shaped design. Thisis placed especially as a heel clip in the rear region of the shoe sole.The insert consists thereby preferably of thermoplastic polyurethane(TPU).

It is also possible, however not preferred due to the higher productionrequirements, that by the blow-molding process several hollows which areseparated from another are produced in the inner of the sole hollow bodywhich are then filled with respective plastic bodies. Those can as thecase may be then have also different physical properties to influenceselectively the spring and damping properties of the shoe sole.

The plastic bodies have preferably a hardness between 75 and 90 Shore A,preferably between 80 and 85 Shore A. They have preferably a bulkdensity between 100 and 300 kg/m³.

It should be mentioned the following with respect to the expandedthermoplastic polyurethane (E-TPU) for the plastic bodies which areimported into the blow-molded sole hollow body which are preferablyused: This material is known as such and is used in shoes. It is forexample available under the name “PearlFoam” from Huntsman InternationalLLC or under the name “Infinergy” from BASF SE. Concerning this materialexplicitly reference is made to WO 2005/066250 A1 where details of thismaterial, thus of expanded thermoplastic polyurethane and itsproduction, can be found.

Furthermore, explicitly reference is made to WO 2010/010010 A1 withrespect to the pre-known thermoplastic elastomer based on urethane inwhich an expanded thermoplastic polymer blend containing a blowing agentis disclosed which contains thermoplastic polyurethane and styrenepolymer. The polymer blend can thereby contain at least one furtherthermoplastic polymer. As further thermoplastic polymer especiallypolyamide (PA), polymethyl methacrylate (PMMA), polycarbonate (PC),polyethylene (PE), polypropylene (PP), polyvinylchloride (PVC),cellulose and polyoxymethylene (POM) respectively can be used.

Thus, according to the invention in a blow-molded sole hollow bodyespecially expanded plastic foam spheres or ellipsoids (eventually alsocylindrically shaped bodies) are used by use of especially E-TPU, E-TPEor EPP (to produce for example very light soles) which are filled intothe created hollow in the sole hollow body (said sole hollow body canalso be denoted as pre-fabricated “cage” for the spheres and ellipsoidsrespectively).

The mentioned supporting structure allows that the sole supports thefoot in an optimal manner under load at intended use. This is essentialunder the aspect that otherwise the plastic bodies which are arranged inthe inner of the sole hollow provide possibly an insufficient supportfunction for the foot due to the fact that the plastic bodies are notconnected with another but are arranged loosely.

The spheres, ellipsoids respectively cylinders, preferably made ofE-TPU, influence significantly the damping of the shoe so that the solepart with the filled hollow is preferably used as midsole.

The sole can be connected with the shoe upper (bootleg) by means ofsewing or gluing which is known as such.

Above, the production of the sole as a complete form part is described.Of course, the invention can also be employed if only a part of the soleis produced as described and is as the case may be connected withanother sole part.

Although the extrusion of a plastic hose and its immediate supply intothe blow mold in the warm state is preferred, alternatively—as mentionedabove—the injection molding of a plastic blank can be provided which isthen supplied to the blow mold. In this case typically at first theinjection molding process for the plastic blank is carried out; when theplastic blank is transferred to the blow molding machine and has to beblow-molded in the same it is again heated up before so that it can bedeformed to the sole hollow body.

BRIEF DESCRIPTION OF THE DRAWING

In the drawing an embodiment of the invention is shown.

FIG. 1 shows schematically a first process step of the production of ashoe sole according to the invention,

FIG. 2 shows the top plan view onto the shoe sole after carrying out theprocess step according to FIG. 1, wherein the sole hollow body of theshoe sole is not yet filled,

FIG. 3 shows schematically the subsequent process step at which the solehollow body of the shoe sole is filled with plastic bodies and

FIG. 4 shows the section A-B according to FIG. 2.

DETAILED DESCRIPTION OF THE INVENTION

In FIG. 1 the start of the production process of a sole structure 20 ofa shoe sole is shown schematically. An extruder 18 plasticizes plasticmaterial and outputs the same via an extrusion head 17 so that a plastichose 2 is produced which is closed around the whole circumference. Whenthe same is long enough it is placed into a blow mold 3 which consistsof two mold halves which are moved against another into the direction ofthe double arrow and then enclose the plastic hose 2 for blow molding inknown manner.

As already mentioned alternatively an injection molding of a plasticblank can be taken in consideration which is then deformed in the blowmold 3.

By the blow molding process a sole hollow body 4 (see FIGS. 2 and 3) isproduced which provides a reception space in its inner.

A first deformation tool 13 and a second deformation tool 15 areschematically indicated. Those tools 13, 15 are moved against another inthe direction of the arrow when the mold halves of the blow mold 3 areclosed. By the tools 13, 15 supporting structures 9 (see FIGS. 2 to 4)are formed into the sole hollow body 4.

A plurality of tools 13, 15 are provided although in FIG. 1 is shownonly one single pair of tools 13, 15.

As can be seen from FIG. 2 a number of the mentioned supportingstructures 9 have been produced presently which are described in detailbelow. For example, illustrated in FIGS. 2 and 3, a first supportingstructure 9 a can be formed in a forefoot region 21, a second supportingstructure 9 b can be formed in the midfoot region 22, and thirdsupporting structure 9 c can be formed in the heel region 23. Eachsupporting structure 9 can provide a supporting function at desiredlocations via the contact area of the foot on the surface of the shoesole 1 so that at the application of the body weight of the wearer ofthe shoe the shoe sole 1 does not yield to the side in an uncontrolledmanner.

Details of the supporting structure are apparent from FIG. 4. Here itcan be seen that the sole hollow body 4 comprises an upper wall 5 and abottom wall 6 which are arranged facing another with a distance aftercarrying out the blow molding process and enclose the mentioned hollowbetween another. By the deformation tools 13 and 15 recesses 7 and 8 areformed at those locations which are apparent from FIG. 2, namely by thefirst deformation tool 13 the recess 7 and by the second deformationtool 15 the recess 8.

Each of the supporting structures 9 defines a longitudinal axis 25 thatextends through the upper wall 5 and intersects a closed end region 14at a peak, illustrated, for example, in FIG. 4. As can be seen therecess 7 has a closed end region 14 and defines a first curved surface26 on a first side of the longitudinal axis 25 and a second curvedsurface 27 on a second side of the longitudinal axis 25, as shown in thecross section of the shoe sole 1 of FIG. 4. The recess 8 has an openingby the second deformation tool 15 which is designed needle-shaped at itsaxial end. This opening is dimensioned in such a manner that the recess7 with its closed end region 14 can at least partially enter into thesame.

The supporting structure 9 which is produced in such a manner preventsrespectively impedes a relative movement between the upper wall 5 andthe bottom wall 6 in horizontal direction (at intended use of the shoewhich has the mentioned shoe sole 1).

When the described sole hollow body 4 is completed insofar the hollow,which is contained in the same, is filled with plastic bodies 10. Thisis illustrated in FIG. 3. For this a filling nozzle 19 is inserted intoan opening 11 in the sole hollow body 4. Then, via the filling nozzle 19sphere-shaped or ellipsoid plastic bodies 10 made of expandedthermoplastic polyurethane (E-TPU) are filled, as the case may besupported by pressurized air, into the sole hollow body 4 between a toeend 28 and a heel end 29 of the sole hollow body 4 until the same iscompletely filled with plastic bodies 10 and the plastic bodies 10 arecompressed against each supporting structure 9 (e.g., against the firstcurved surface 26 and the second curved surface 27). With respect to thematerial of the plastic bodies 10 hints to respective publications arealready given above.

It is essential that the plastic bodies 10 are filled into the hollow ofthe sole hollow body 4 quasi as loose material and are placed in thehollow unconnected with another. Accordingly the plastic bodies 10 arefree from any connection with another. The plastic bodies 10 indeedstabilize mutually after filling of the sole hollow body 4, but arearranged loosely to another.

Hereby not only the damping behavior of the sole and thus of the shoecan be influenced very beneficially; also the production process is easyand can be carried out cost-efficiently.

By the evacuation of air, i.e. by the application of a vacuum at asecond opening 12 of the sole hollow body, the filling process can besupported and as the case may be after completion of the same air can beevacuated from the inner of the sole hollow body 4 (see arrow at theopening 12).

The openings 11 respectively 12 can be closed after completion of thefilling process with plastic bodies 10. Here, especially a welding ofthe openings is taken in consideration. So, a hermitically closed hollowis created in the shoe sole 1 which is filled with the loosely arrangedplastic bodies 10.

In cooperation with the supporting structure 9 the possibility is givento influence the spring and damping behaviors of the shoe sole in acertain range arbitrarily but to take care nevertheless that a good holdfor the foot at good stability of the sole is given at the intended useof the shoe which is provided with the shoe sole.

In FIG. 2 also a preferred embodiment of the described process isillustrated: Here, a U-shaped insert 16 can be seen which is insertedprior to the closing of the blow mold 3 into the cavity of the same. Bythe blow molding process the insert 16 is firmly connected (welded) withthe plastic hose 2 respectively the sole hollow body 4.

The insert 16 can be used to influence selectively the supportingfunction of the shoe sole 1. Preferably, the insert 16 is used as heelshell which supports the foot of the user of the shoe which is equippedwith the shoe sole in the rear region and namely in the region of theheel.

1 Shoe sole

2 Plastic hose

3 Blow mold

4 Sole hollow body

5 Wall

6 Wall

7 Recess

8 Recess

9 Supporting structure

10 Plastic body

11 First opening

12 Second opening

13 First deformation tool

14 Closed end region

15 Second deformation tool

16 Insert

17 Extrusion head

18 Extruder

19 Filling nozzle

20 Sole structure

21 Forefoot region

22 Midfoot region

23 Heel region

25 Longitudinal axis

26 First curved surface

27 Second curved surface

28 Toe end

29 Heel end

We claim:
 1. A shoe, comprising: a sole structure defining a first supporting structure, a second supporting structure, and a third supporting structure, the first supporting structure being disposed within a forefoot region, the second supporting structure being disposed within a midfoot region, and the third supporting structure being disposed within a heel region, wherein each of the first supporting structure, the second supporting structure, and the third supporting structure define at least one curved surface, against which a plurality of plastic bodies are disposed, wherein the plurality of plastic bodies comprise foamed plastic, define spheres or ellipsoids, are between 1 mm and 13 mm in the three spatial directions, and are arranged loosely within the sole structure without connection to one another, and wherein the plurality of plastic bodies are compressed against the first supporting structure, the second supporting structure, and the third supporting structure.
 2. The shoe of claim 1, wherein each of the first supporting structure, the second supporting structure, and the third supporting structure defines a longitudinal axis, and wherein the at least one curved surface of each of the first supporting structure, the second supporting structure, and the third supporting structure includes a first curved surface on a first side of the longitudinal axis, and a second curved surface on a second side of the longitudinal axis, opposite the first side.
 3. The shoe of claim 2, wherein the first curved surface and the second curved surface are joined at a peak.
 4. The shoe of claim 1, wherein at least a portion of each of the first supporting structure, the second supporting structure, and the third supporting structure is integrally formed with a bottom wall of the sole structure.
 5. The shoe of claim 1, wherein the plurality of plastic bodies are provided between a toe end of the sole structure and the first support structure, between the first support structure and the second support structure, between the second support structure and the third support structure, and between the third support structure and a heel end of the sole structure.
 6. The shoe of claim 1, wherein the second supporting structure is disposed at a midpoint between the first supporting structure and the third supporting structure.
 7. The shoe of claim 1, wherein each of the first supporting structure, the second supporting structure, and the third supporting structure define an upper wall and a bottom wall, and wherein the at least one curved surface is defined by the upper wall.
 8. The shoe of claim 1, wherein the plurality of plastic bodies are selected from the group consisting of expanded thermoplastic polyurethane, expanded thermoplastic elastomer, and expanded polypropylene.
 9. A shoe, comprising: a sole structure defining a hollow body and including a first supporting structure, a second supporting structure, and a third supporting structure, the first supporting structure being disposed within a forefoot region, the second supporting structure being disposed within a midfoot region, and the third supporting structure being disposed between a heel end of the sole structure and the second supporting structure, wherein each of the first supporting structure, the second supporting structure, and the third supporting structure defines a longitudinal axis with a first curved surface being disposed on a first side of the longitudinal axis and a second curved surface being disposed on a second side of the longitudinal axis, wherein a plurality of plastic bodies are compressed against each of the first curved surfaces and the second curved surfaces, wherein each of the plurality of plastic bodies is loosely arranged within the sole structure, and wherein the plurality of plastic bodies comprise foamed plastic, define spheres or ellipsoids, and are selected from the group consisting of expanded thermoplastic polyurethane, expanded thermoplastic elastomer, and expanded polypropylene.
 10. The shoe of claim 9, wherein the first curved surface and the second curved surface are joined at a peak and the longitudinal axis extends through the peak.
 11. The shoe of claim 10, wherein the plurality of plastic bodies are provided between a toe end of the sole structure and the first support structure, between the first support structure and the second support structure, between the second support structure and the third support structure, and between the third support structure and the heel end of the sole structure.
 12. The shoe of claim 10, wherein at least a portion of each of the first supporting structure, the second supporting structure, and the third supporting structure is integrally formed with a bottom wall of the sole structure.
 13. The shoe of claim 9, wherein the first supporting structure is disposed entirely within the forefoot region, the second supporting structure is disposed entirely within the midfoot region, and the third supporting structure is disposed within a heel region of the sole structure.
 14. The shoe of claim 9, wherein the second supporting structure is disposed at a midpoint between the first supporting structure and the third supporting structure.
 15. A shoe, comprising: a sole structure defining a first supporting structure, a second supporting structure, and a third supporting structure, the first supporting structure being disposed within a forefoot region, the second supporting structure being disposed within a midfoot region, and the third supporting structure being disposed within a heel region of the sole structure, wherein each of the first supporting structure, the second supporting structure, and the third supporting structure extend from a bottom wall of a sole structure toward an upper, and define a curved surface, wherein a plurality of plastic bodies are compressed against the curved surface, wherein the plurality of plastic bodies comprise foamed plastic, define spheres or ellipsoids, are between 1 mm and 13 mm in the three spatial directions, and are arranged loosely within the sole structure without connection to one another, and wherein the plurality of plastic bodies are compressed against the first supporting structure, the second supporting structure, and the third supporting structure.
 16. The shoe of claim 15, wherein each of the first supporting structure, the second supporting structure, and the third supporting structure defines a longitudinal axis, and wherein the curved surface of each of the first supporting structure, the second supporting structure, and the third supporting structure includes a first curved surface on a first side of the longitudinal axis, and a second curved surface on a second side of the longitudinal axis, opposite the first side.
 17. The shoe of claim 15, wherein the plurality of plastic bodies are provided between a toe end of the sole structure and the first support structure, between the first support structure and the second support structure, between the second support structure and the third support structure, and between the third support structure and a heel end of the sole structure.
 18. The shoe of claim 15, wherein the first supporting structure is disposed entirely within the forefoot region and the second supporting structure is disposed entirely within the midfoot region.
 19. The shoe of claim 15, wherein the second supporting structure is disposed at a midpoint between the first supporting structure and the third supporting structure.
 20. The shoe of claim 15, wherein at least a portion of each of the first supporting structure, the second supporting structure, and the third supporting structure is integrally formed with a bottom wall of the sole structure. 